Document FR-A-2,590,959 describes a device for gripping an optical fiber. That device is constituted by a body and a clamping jaw, and it has an overall shape that is suitable for it to be held in a system having a cylindrical clamping chuck or three jaws at 120.degree. engaging the periphery of the body.
In that known device, the body has two parallel and opposite side flats. A first one of the flats defines a plane surface provided with a rectilinear groove in which the sheathed fiber can be positioned. The fiber installed in the groove remains proud relative to the plane surface of the first flat. The jaw is pivotally mounted to rotate about a pin that is parallel to the groove, which pin secures the jaw to the body, and enables the jaw to be put either in the open position or in the closed position against the first flat. The jaw itself has a plane abutment surface that bears resiliently against the sheathed fiber installed in the groove, when the Jaw is in the closed position. The resilience is provided by the jaw having a slot in the vicinity of the abutment surface so that said abutment surface can be deformed. When that jaw is in the closed position, its abutment surface is not parallel to the grooved plane surface of the body, and it is not possible for a plurality of fibers disposed side-by-side to be retained thereby.
That device further includes means for opening the jaw, which means are constituted by springs working in compression. That device also includes locking means for locking the jaw in a limited open position, and in a closed position, the limited open position being just sufficient to enable the sheathed fiber to be passed and installed in the groove. Those locking means are relatively complex. They are situated against the second flat and are difficult to access.